Printronix PrintNet Enterprise - Manual (Page 277)

Voltages
277
CAUTION For safety purposes do not apply a voltage greater than 42 volts DC to
the GPIO board, even though the relay is rated at 220 volts DC.
Voltages
Two voltages available on the I/O connector are 5 and 24 volts DC. Using
self-healing fuses, both voltages are separately fused at 500 mA for 5 volts
and 250 mA for 24 volts. These voltages share the same ground. To
guarantee complete galvanic isolation between the printer and the equipment
that is connected through the GPIO interface, use a separate power source
for the equipment the printer is connected to and make sure the I/O connector
housing on the printer side is not connected to ground.
NOTE: Be aware that the 24 volts require a special connection inside the
printer and that this voltage is not available when a cutter is installed
in the Thermal printer.
I/O Connector
The I/O connector is a 3 row, 50 pin, D type connector. Inputs and outputs of
opto-couplers and relays are wired to this connector so that creating inputs
using common anodes or cathodes or outputs using common emitters or
collectors is fairly simple. The two voltages and their respective returns are
also wired to this connector.
Table 14 specifies the connector wiring where IPxA represents the anode
connection of the Input Opto Coupler diode and IPxC represents the cathode
connection of the diode. OPxC represents the collector of the output
transistor, and OPxE represents the emitter of the transistor. RxCM
represents the common connection of the SPDT relay contact, RxNC
represents the Normally Closed, and RxNO the Normally Open contact.